This invention relates to the field of illumination and display devices, and more particularly to dynamic image displays.
Over the years, a variety of dynamic image display techniques have been developed, including the modulation of one or more flames, incandescent elements, electron-beam or ultraviolet-excited fluorescent patches, light emitting semiconductors, or other sources of light. Most of these techniques involve modulation of the power source responsible for the illumination of each picture element (pixel) in the image. Examples of these techniques include traffic lights, cathode ray tubes, and light emitting diode (LED) displays.
A second class of display techniques involves generation of light followed by its separate modulation for each pixel. An example of this is film projection where the image on the film selectively absorbs the light for each pixel, and the image changes as the film advances. The example most relevant to the present invention is liquid crystal displays which modulate ambient light to produce dynamic images for watch faces, computer displays and now even color television sets. In general, these techniques for producing compact flat displays are not economic or do not produce brilliant images.
In the field of data processing and communications, light waveguides have been used to guide coherent light. Information can be transferred by the use of switches such as the one disclosed by Giallorenzi et al. in U.S. Pat. No. 3,980,395. By selectively applying an electric field to liquid crystal cells, Giallorenzi can selectively couple or filter waveguide modes. This switch relies upon the phenomena of light by which a mode will only be coupled out of the guide when a liquid crystal's index exceeds the effective modal index. It is the object of the present invention to take advantage of this phenomena to provide a new and improved visual display.
It is the further object of the present invention to provide an improved method and apparatus for display of bright dynamic black and white or color images containing one or more pixels.